In the manufacturing field of a printed wiring board as a resist material to be used for etching, plating, etc. a photosensitive resin composition, and a photosensitive element (layered body) with a structure constituted with a layer formed using such a photosensitive resin composition (hereinafter also referred to as “photosensitive resin layer”) layered on a support film, and a protection layer placed on the photosensitive resin layer have been heretofore widely used.
A printed wiring board is manufactured using the photosensitive element, for example, according to the following procedures. First of all, a photosensitive resin layer of the photosensitive element is laminated on a substrate for circuit formation such as a copper-clad laminate board. In doing so, lamination is performed such that the surface opposite to a surface in contact with a support film of a photosensitive resin layer (hereinafter also referred to as “upper surface” of a photosensitive resin layer) contacts tightly a surface, on which a circuit is to be formed, of the substrate for circuit formation. Therefore, in a case where a protection layer is placed on the upper surface of the photosensitive resin layer, the lamination work is carried out, while the protection layer is peeled off. Meanwhile, the lamination is conducted by compression bonding a photosensitive resin layer to a basis substrate for circuit formation with heating (normal pressure lamination method).
Next, a photosensitive resin layer is exposed in a pattern through a mask film, etc. In this case a support film is detached at an any timing before or after exposure. Thereafter, an unexposed part of the photosensitive resin layer is removed by dissolution or dispersion using a developing solution. Next, a conductor pattern is formed by carrying out an etching treatment, or a plating treatment, and finally a cured part of the photosensitive resin layer is detached and removed.
With respect to a technique for the pattern exposure, a projection exposure method has been recently introduced, by which a photosensitive resin layer is irradiated in a form of an image with active light projecting an image of a photomask through a lens for exposing a photosensitive resin layer. A projection exposure method is able to secure higher resolution, higher aspect ratio, and higher alignment compared to a contact exposure method using a mask film, etc. Therefore, in view of recent trend that a fine conductor pattern is required for a printed wiring board, a projection exposure method has drawn intense attention.
Meanwhile, in a projection exposure method, monochromatic light such as i line monochromatic light (365 nm) is used generally for obtaining a fine conductor pattern, and therefore compared to an exposure method using parallel light of ihg mixed lines the irradiation energy dose is small so that an exposure time tends to be longer. Further, although an exposure method using parallel light is based on a one-shot exposure method, a projection exposure method adopts a split exposure method, and therefore the overall exposure time tends to be further extended. Consequently, the illuminance of a projection exposure device is designed higher than that of a parallel light exposure device in order to shorten the overall exposure time, and the exposure time of a projection exposure device per exposure tends to become shorter than a parallel light exposure device.
In line with the development of a projection exposure method having such characteristics, a photosensitive resin composition able to form a resist pattern with superior adherence even by a projection exposure method providing a short exposure time per exposure has been considered (for example, see Patent Literature 1).